The present invention relates to a liquid-coolant cooling element for cooling heat-generating disk-shaped components.
Liquid-coolant cooling elements are known for cooling power semiconductor components. The increase in the switching power of semiconductor components is coupled with the generation of a higher heat loss. In general, liquid-coolant cooling elements have a larger cooling power and more easily resist the shock and transition conditions, since their thermal inertia enables short thermal pulses to be equalized with only a slight increase in temperature. The cooling elements are constructed in many cases as cylindrical or cuboid elements with supply and discharge connecting pieces. In the interior of the cooling element a system of channels is constructed which are either parallel or otherwise connected to each other. In some cases, the distribution of the cooling liquid is carried out using constructed partitions. Alternatively, various erections of pins are placed in the path of the liquid flow. All these arrangements are used for increasing the contact surface which transmits the heat to the cooling liquid.
German Patent Document No. DE-A-16 39 047 discloses a cooling element arrangement for semiconductor components which comprises a cooling element, a reversing piece and an end piece. The cooling element and the reversing piece are provided with channels. These cooling and reversing channels preferably have the same shape and dimensions and are offset with respect to each other in such a way that at least two adjacently located cooling channels are connected to each other by a reversing channel. This reversing piece can comprise metal or plastic. Apart from the reversing channels, it contains outflow channels located on the periphery and a centrally located inflow channel. This reversing piece is included in the end piece and is fastened with the latter to the surface of the cooling element facing away from the semiconductor body. The end piece contains a circular ring-shaped collecting channel which is arranged such that all the outflow channels of the reversing piece open into it. Furthermore, this collecting channel is connected to an outlet. An inlet in the end piece is located opposite the opening of the inflow channel of the reversing piece. Because of this configuration of the cooling element arrangement, the coolant runs between the inlet and outlet underneath the surface to be cooled of the semiconductor body, in serpentine fashion. The reversing piece and the end piece can also form one constructional unit.
If the cooling element arrangement comprises a plurality of parts, the contact surfaces between the latter parts must be machined such that a tight seal results, or corresponding seals must be laid between them. Furthermore, the expenditure for producing this cooling element arrangement is very large, since the cooling channels in the cooling element and the reversing channels in the reversing piece must be constructed very accurately in order that the opening of each reversing channel is located directly opposite parts of the opening of at least two cooling channels in the assembled condition.
A cooling can is disclosed in German Patent Document No. DE-A-19 14 790 which is composed of an essentially rectangular connection plate and two cooling pots arranged around the connection plate. The cooling pots have relatively wide and thick collars at the periphery, which are used for the screw connection to the connection plate. That part of the connection plate projecting beyond the cooling pots is simultaneously used as a current connection. The cooling pots contain on the inside a liquid distributor in the form of a plurality of webs which are connected to a central passage and an eccentric passage, with the result that an asymmetrical liquid flow with a relatively large pressure drop prevails in the interior of the cooling pots. A relatively large thermal resistance is produced by this reduction of the pressure drop. The thermal resistance states how much heat can be led away from the disk-shaped semiconductor cell to the coolant. In addition, the heat exchange surface is limited by the constructional shape of the cooling pots. The heat exchange surface is defined as that part of the surface of the cooling pots which is directly swept over by the cooling liquid.
A cooling can is disclosed in German Patent Document No. DE-B-21 60 302 which comprises two round cooling pots, with their two flat heat transfer surfaces resting on the wafer cells, and a plate-shaped connection piece, for cooling liquid and current connections, located between said cooling pots and connected to them in a sealing fashion. The connection piece has inlet and outlet channels directed inward from the edge and each opening into a passage opening which is approximately at right angles to them and penetrates the connection piece. The cooling liquid passes via the inlet channel, the first passage opening, cooling pots and the second passage opening to the output channel. The connection piece is a circular plate having radially aligned inlet and outlet channels flush on the same side and passage bores arranged symmetrically with respect to the center of the connection piece. The cooling pots have, on their side facing the connection piece, uninterrupted concentric annular channels, the partitions of which reach as far as the ends of the connection piece and each of which is connected in terms of flow to the passage bores.
This construction of the cooling pots allows a simple production of these parts as turned parts in automatic turning machines. By means of the use of concentric and uninterrupted annular channels for guiding the cooling liquid, all mutually parallel annular channels being fed simultaneously with cooling liquid from the inlet channel via the passage bore, a very low thermal resistance of the cooling can is achieved. Furthermore, the guiding of coolant in mutually concentric annular channels enables the utilization of the entire surface of the cooling can as a heat exchange surface.
If more than two disk-shaped components have to be cooled, further cooling cans are needed, which are linked together with these disk-shaped components to form a clamped assembly. In consequence, additional liquid connections are necessary. Furthermore, in each case only disk-shaped components having the same diameter can be arranged in one common clamped assembly. Furthermore, a clamped assembly of this type needs sufficient space, a high packing density not being achieved.